Rf treatment apparatus, method of controlling rf treatment apparatus and skin treatment method using rf energy

ABSTRACT

The present invention relates to an RF treatment apparatus, the method of controlling the RF treatment apparatus and the skin treatment method using RF energy according to the present invention have an effect in that they can improve the accuracy and efficiency of treatment because whether a target tissue corresponds to a treatment temperature is determined based on impedance of the tissue and the volume of the target tissue corresponding to the treatment temperature can be maximized while maintaining the target tissue to the treatment temperature for a predetermined time.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 16/070,495, filed Jul. 16, 2018, which is a U.S.National Stage of PCT/KR2018/002436, filed Feb. 28, 2018, which claimsthe priority benefit of Korean Patent Application No. 10-2017-0041801,filed on Mar. 31, 2017, in the Korean Intellectual Property Office, thedisclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an RF treatment apparatus, a method ofcontrolling the RF treatment apparatus, and a skin treatment methodusing RF energy and, more particularly, to an RF treatment apparatuscontrolling RF energy using calculated impedance, a method ofcontrolling the RF treatment apparatus, and a skin treatment methodusing RF energy.

BACKGROUND ART

A method of treating a tissue may be divided into a method of treating atissue outside the tissue and an invasive treatment method of treating atissue by inserting some of or the entire treatment apparatus into thetissue. The invasive treatment method basically uses a treatmentapparatus having a thin-necked insertion unit, such as a needle or acatheter. Treatment is performed after the treatment apparatus isinserted into a target location within a tissue.

The invasive treatment method includes various treatment behaviors, suchas delivering a treating substance to the inside of a tissue, performingsurgical treatment through a mechanical operation in the state in whicha predetermined tissue within a tissue is adjacent, or delivering energyto a target location within a tissue. The treatment method has beendisclosed in Korean Patent Application Publication No. 10-2011-0000790,and is applied in various methods.

However, the existing RF treatment apparatus has a problem in that atissue may be damaged because excessive energy is applied when applyinghigh energy within a short time.

DISCLOSURE Technical Problem

The present invention has been made to solve the aforementioned problemof the conventional RF treatment apparatus, and an object of the presentinvention is to provide an RF treatment apparatus capable of cutting offRF energy prior to excessive damage to the skin, a method of controllingthe RF treatment apparatus, and a skin treatment method using RF energy.

Technical Solution

As means for solving the object, there may be provided an RF treatmentapparatus, comprising an RF generator generating RF energy, an electrodeapplying the RF energy to a target tissue, a sensor unit configured tosense the RF energy and a controller controlling output of the RFgenerator, receiving a sensing value from the sensor unit, calculatingimpedance of the target tissue, and cutting off the RF energy if theimpedance is determined to have increased for a specific period.

In this case, the controller determines the impedance to have increasedfor the specific period when a parameter value exceeds a threshold, andthe parameter value is defined as a product of a specific time and theimpedance of the tissue.

Furthermore, the parameter is defined as a product of a rising time froma current time to the predetermined time before and impedance for therising time.

In this case, the rising time is a case where the impedance continues tohave increased from the current time to the predetermined time before.

Furthermore, The RF treatment apparatus of claim 2, wherein theparameter value is defined as a product of the specific time and anaverage of the impedance for the predetermined time.

Furthermore, the parameter value is defined as a product of the specifictime and an average of changes in the impedance for the specific time.

Furthermore, a case where the impedance is determined to have increasedfor the specific period is a case where a change in the impedancecontinues to have increased for the specific period.

Meanwhile, the threshold is determined in accordance with a temperatureat which the tissue is not ablated when the temperature of the tissuerises as the RF energy is applied.

Furthermore, the threshold is determined to be a value when atemperature of the tissue is 70° C. as the RF energy is applied.

Moreover, the sensor unit measures current, a voltage and power appliedto the electrode and the controller calculates the impedance as a rootmean square (RMS) when calculating the impedance.

Moreover, wherein the controller controls an output voltage of the RFgenerator so that the power does not exceed a specific range.

Furthermore, the electrode comprises at least one of a contact type andan insertion type.

In Addition, there may be provided a method of controlling an RFtreatment apparatus, comprising steps of applying RF energy to a tissuethrough an electrode, calculating impedance of the tissue, calculating aparameter defined as a product of a specific period of a time duringwhich the RF energy is applied and impedance calculated in the specificperiod, and determining whether the parameter exceeds a threshold andcutting off the RF energy when the parameter exceeds the threshold.

Meanwhile, the parameter is defined as a product of a rising time from acurrent time to the specific time and impedance for the rising time.

Furthermore, the parameter is defined as a product of a rising time froma current time to a specific time and a change in the impedance for therising time.

Moreover, the parameter is defined as a product of a rising time from acurrent time to a predetermined time before and an average of changes inthe impedance for the rising time.

Furthermore, the step of determining whether the parameter exceeds thethreshold is performed after a specific time from a point of time atwhich the RF energy is applied.

Furthermore, the threshold is determined in accordance with atemperature at which the tissue is not ablated when the temperature ofthe tissue rises as the RF energy is applied.

Meanwhile, the step of positioning the electrode in the tissue isperformed by at least one of a contact and insertion of the electrode onand into the tissue.

In addition, there may be provided a method of controlling an RFtreatment apparatus, comprising steps of applying RF energy to a tissuethrough an electrode, calculating impedance of the tissue, determiningwhether a parameter defined as an average of impedance of the tissuefrom a current time to a specific time exceeds a threshold and cuttingoff the RF energy when the parameter exceeds the threshold.

In Addition, there may be provided a skin treatment method In this case,the comprising steps of positioning an electrode in a tissue, heatingthe tissue to a treatment temperature by applying RF energy to theelectrode, measuring the RF energy applied to the tissue, calculatingimpedance of the tissue to which the RF energy is applied, comparing aparameter into which impedance from a current time to a predeterminedtime before has been incorporated with a threshold and determiningwhether to cut off the RF energy based on a result of the comparisonbetween the parameter and the threshold in order to prevent ablation ofthe tissue.

In this case, determining whether to cut off the RF energy based on aresult of the comparison comprises continuing to apply the RF energywhen the parameter is less than the threshold and cutting off the RFenergy when the parameter is the threshold or more.

Meanwhile, the parameter is defined as any one of an average ofimpedance values measured during a time interval from a current time toa specific time, a product of impedance values, a change in theimpedance value, and an average of changes in the impedance values.

DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram of an RF treatment apparatus according tothe present invention.

FIG. 2 is a diagram showing an impedance change according to atemperature rise of a tissue.

FIGS. 3 a and 3 b are conceptual diagrams when ablation within a tissueoccurs.

FIGS. 4 a and 4 b are impedance and temperature graphs of a tissue whenablation occurs.

FIGS. 5 a and 5 b are graphs of impedance in the ablation preventionmode.

FIG. 6 is a flowchart of a method of controlling an RF treatmentapparatus in the ablation prevention mode.

FIGS. 7 a and 7 b are impedance and temperature graphs of a tissue whenthe ablation prevention mode is performed.

FIGS. 8 a, 8 b and 8 c are conceptual diagrams of when coagulationwithin a tissue occurs.

FIG. 9 is a graph showing RF energy measurement values when RF energy isapplied within a tissue.

FIG. 10 is a flowchart of the coagulation mode.

FIG. 11 is a detailed flowchart of an energy control step in FIG. 10 .

FIGS. 12 a and 12 b are graphs showing RF energy measurement values whenthe coagulation mode is performed.

FIG. 13 is a perspective view of an RF treatment apparatus according tothe present invention embodiment.

FIG. 14 is an enlarged perspective view of a handpiece of FIG. 13 .

MODE FOR INVENTION

Hereinafter, an RF treatment apparatus, a method of controlling the RFtreatment apparatus, and a skin treatment method using RF energyaccording to embodiments of the present invention are described indetail with reference to the accompanying drawings. Furthermore, in thefollowing description of the embodiments, elements may be nameddifferently in the field to which the present invention pertains.However, if the elements have functional similarity and identity, theymay be considered to be equivalent elements although they adopt modifiedembodiments. Furthermore, reference numerals assigned to respectiveelements are written for convenience of description. However, contentsshown in the drawings in which the reference numerals are written do notrestrict respective elements to the ranges in the drawings. Likewise,although the elements in the drawings adopt partially modifiedembodiments, they may be considered to be equivalent elements if theelements have functional similarity and identity. Furthermore, adescription of an element is omitted if the element is recognized asbeing an element that must be naturally included in view of the level ofa person having ordinary skill in the art.

Hereinafter, a “treatment apparatus” includes all apparatuses fortreating mammals including people. The treatment apparatus may includemay include various treatment apparatuses used to improve a lesion orthe state of a tissue. For example, the treatment apparatus includes anapparatus transferring treating substances, such as medicines,anesthetic, and stem cells, an operation apparatus for surgicallytreating a predetermined tissue, and various treatment apparatusesapplying RF energy.

Hereinafter, a “tissue” means a set of cells forming various body organsof an animal including people, and includes various tissues formingvarious organs within the body, including a skin tissue.

FIG. 1 is a conceptual diagram of an RF treatment apparatus according tothe present invention. The RF treatment apparatus is configured to treata tissue by applying RF energy to the inside of the tissue to denaturizethe tissue. As shown, the RF treatment apparatus according to thepresent invention may include an electrode 2, an RF generator 3, a powersupply 4, a sensor unit 7, a controller 5 and a reference unit.

The electrode 2 is configured to apply RF energy from the RF treatmentapparatus to the skin. A plurality of electrodes 2 may be configured toapply energy to a plurality of points. The electrode 2 has a bipolartype, and may be configured so that RF energy is concentrated on alesion portion positioned between each of pairs of the electrodes 2.Furthermore, a plurality of pairs of electrodes 2 is provided, and maybe configured to generate fractional damage within a tissue. Theplurality of electrodes 2 may be configured in an insertion and/orcontact type. If the electrodes are configured in the insertion type, aplurality of micro needles may be configured to be inserted into a skintissue and to generate heat in a deep part. Furthermore, if theelectrodes are configured in the contact type, they may come intocontact with the skin and generate deep part heat. In this case, aninsulating part may be applied to each electrode 2 so that an RF energytransmission condition is changed. In this case, the configuration ofthe electrode 2 may be modified and applied in various manners, and thusa further detailed description thereof is omitted.

The RF generator 3 is configured to be supplied with power from thepower supply 4 and to generate RF energy. The RF generator 3 generatesRF energy used for treatment through the electrode 2. In this case, theRF generator 3 is configured to change the frequency, voltage, etc. ofthe RF energy, if necessary.

The sensor unit 7 is configured to measure an output value of RF energy.The sensor unit 7 may be provided on an electrical path between theelectrodes 2 from the RF generator 3, and is configured to measurecurrent, a voltage and power applied to the electrodes 2. An impedancevalue of a tissue can be calculated based on the current, a voltage andpower.

The controller 5 is configured to receive a sensing value from thesensor unit 7 and to control the RF generator 3. Furthermore, thecontroller 5 is configured to control the RF generator 3 and otherelements when operating in various modes in response to a user input.The controller 5 may function to determine the state within a tissuewhile RF energy is applied and to control the applied RF energy or blockthe RF energy based on the state of the tissue. In this case, thecontroller 5 may determine the state within the tissue or output of theRF energy based on data stored in the reference unit. Meanwhile,although the reference unit is not provided, the controller 5 mayperform control using a predetermined setting value.

Hereinafter, RF energy applied to the inside of a tissue, a temperatureof the tissue, and a change in the state of the tissue are describedwith reference to FIG. 2 .

FIG. 2 is a diagram showing an impedance change according to atemperature rise of a tissue. When RF energy is applied, a tissue isdenaturized. Such denaturalization may be divided into a heat phase, acoagulation occurrence phase, a desiccation occurrence phase and avaporization occurrence phase. The heat phase corresponds to the sectionin which a tissue rises up to a treatment temperature as RF energy isapplied. In this case, when the temperature of the tissue reaches about44° C. , tissue necrosis begins. Thereafter, when the temperature of thetissue reaches about 70° C., coagulation of the tissue starts.Thereafter, when the temperature of the tissue reaches about 90° C.,desiccation occurs. In this case, cells lose moisture, but theultrastructure of the tissue may remain intact. Thereafter, when thetemperature of the tissue reaches 100° C., moisture starts to bevaporized. When the tissue is further heated, carbonization occurs about200° C.

Impedance of the tissue at this time is described. When RF energy of thesame power is applied, the tissue is denaturized and an impedance valueis greatly changed depending on a temperature rise of the tissue. Thatis, in the heat phase, after a sudden rise of the impedance, astabilization phase in which a change (ΔZ) in the impedance is reducedappears. This corresponds to the coagulation occurrence phase.Thereafter, a phase in which a sudden rise of the impedance occurscorresponds to the desiccation occurrence phase. In contrast, thecurrent state of a tissue may be estimated by measuring impedance of thetissue and checking a variation tendency. Predeterminedally, it may beseen that after the RF energy is applied, if an impedance value isstabilized within a predetermined range after a lapse of a predeterminedtime, temperature of the tissue is about 70° C. and coagulation occurs.Thereafter, it may be seen that when a sudden rise of the impedanceoccurs, the impedance becomes the desiccation occurrence phase in whichablation occurs.

In other words, an important factor in the aspect of control of atemperature of a tissue and energy based on the temperature is impedanceof the tissue. The impedance of the tissue tends to be generally similaraccording to a temperature change (as a treatment time elapses). Anincrement phase and a sudden increment phase appear after the phase inwhich impedance of a tissue is gradually decreased.

The controller performs control based on a calculated impedance value sothat RF energy is optimized and applied depending on treatment purposes.For example, the controller may perform control so that a local portionis denaturized until right before ablation for the purposes of removalof a scar, removal of a tissue, etc., or coagulation occurs in a widevolume for the retightening of the skin.

Hereinafter, two treatment modes of the functions of the controller aredescribed. An ablation prevention mode is described with reference toFIGS. 4 to 7 , and a coagulation mode is described with reference toFIGS. 8 to 12 . In this case, each mode may be optionally applied by auser.

I. Ablation Prevention Mode

FIGS. 3 a and 3 b are conceptual diagrams when ablation within a tissueoccurs. FIGS. 4 a and 4 b are impedance and temperature graphs of atissue when ablation occurs. FIGS. 5 a and 5 b are graphs of impedancein the ablation prevention mode. FIG. 6 is a flowchart of a method ofcontrolling an RF treatment apparatus in the ablation prevention mode.FIGS. 7 a and 7 b are impedance and temperature graphs of a tissue whenthe ablation prevention mode is performed.

Referring to FIG. 3 a , there are shown a region denaturized becausecoagulation has occurred in a tissue (i) and a region in which ablationhas occurred (ii) thereafter. This corresponds to a case where theablation region is expanded because a temperature of a tissue around theelectrode rises rapidly compared to the speed at which the region wherecoagulation has occurred is expanded. Accordingly, the ablationprevention mode is applied to prevent ablation in the tissue and todenaturize a proper region.

Referring to FIGS. 4 a and 4 b , there are shown temperatures andimpedance when RF energy is applied to different persons. As shown,although the RF energy is applied with the same power for the sameapplication time, points of time at which the temperature rises suddenlyare different in the persons. Accordingly, if the RF energy is notcontrolled, unwanted damages may occur. For example, if RF energy havingpower of 20 W is applied for 0.5 second, unlike in FIG. 4 a , ablationoccurs in the case of FIG. 4 b and thus damage to a tissue occurs.Accordingly, the controller blocks power in a step prior to theoccurrence of ablation at a predetermined point of time in order toprevent such damage.

The function of the controller 5 is described below based on a samplingtime T. The controller 5 controls the RF generator 3 so that power of RFenergy is controlled or the RF energy is blocked. Power control of theRF generator 3 is first described below.

To constantly maintain power of RF energy applied to a tissue duringtreatment is preferred in terms of the prevention of damage to thetissue attributable to the sudden application of energy, the treatmentrange of the tissue, and accuracy of a treatment effect. In this case,if a method of measuring a temperature within the tissue is used, timedelay occurs due to the temperature measurement, and thus control of theoutput of the RF energy is not properly incorporated. Accordingly, it ispreferred to measure and incorporate impedance of the tissue, but a finechange in the volume occurs if fractional damage occurs. Furthermore,since treatment is performed within a short time, an impedance value,that is, an electrical characteristic of the tissue, may be sensitivelychanged. Accordingly, temperature measurement is used for controlthrough a predetermined step.

Accordingly, an impedance effective value (i.e., root-mean-square (RMS))of a tissue may be obtained based on values obtained by measuring avoltage, current and power continuously (at T intervals) using thesensor unit 7 while RF energy is applied.

Detailed contents are described below.

At a point of time T that is an initial step 1, an R1 value may bederived as the RMS of a voltage V1, current I1 and power P1.

Thereafter, at a point of time 2T that is step 2, R2 may be derived asthe RMS of a voltage V2, current I2 and power P2.

In this case, referring to a power relation in step 1 and step 2, apower loss occurs due to a change in the reactance. At this time, apower factor may be defined as follows.

φ=PRMS(t)/PRMS(t−1)

In this case, the power factor becomes a reactance value in step 2.Accordingly, the reactance value in step 2 can be obtained although theimpedance value of the tissue is not measured.

An example of detailed numerical values is shown in Table 1.

TABLE 1 STEP 1 2 3 4 V [V] 1 1 1 1 I [A] 1 2 2 1 P [W] 1 2 2 1 Powerfactor — 2 1 1.5 Resistance 1 0.5 0.5 1 [Ω] Reactance — 2 1 1.5

As described above, the impedance value of the tissue is calculated ineach step. Power suitable for a corresponding tissue based on animpedance value is determined by matching the impedance value with datastored in the reference unit 6. Thereafter, the tissue can be properlytreated within a short time by controlling an output voltage of the RFgenerator 3 so that RF energy of a determined power value is applied.

The cutting off of RF energy, that is, a function of the controller 5,is described below.

The controller 5 may be configured to block applied RF energy if itdetermines that impedance has suddenly increased for a predeterminedperiod. This is for preventing ablation occurring due to a sudden riseof a tissue temperature.

The controller 5 may determine that impedance has increased for apredetermined period based on a parameter value defined as the productof a rising time “Trising”, that is, a predetermined period during whichimpedance has increased, and the mean (Zvalue) of impedancecorresponding to the rising time “Trising” as follows.

Parameter=Trising×Zvalue

A determination of whether impedance has increased for a predeterminedperiod is described based on a sampling period T. Whether impedance hasincreased is determined for a time interval from the present point oftime to a predetermined time. In this case, if the rising time, that is,the time from the current time to the predetermined time, is too large,rapid handling is difficult. If the rising time is too small, it may besensitive to low noise. Accordingly, it is preferred to properlydetermine the rising time.

FIGS. 5 a and 5 b are graphs of impedance in the ablation preventionmode. As shown, whether a parameter exceeds a first threshold isdetermined every step after a predetermined time. A case where apredetermined time interval is three sampling time intervals isdescribed as an example with reference to FIG. 5 a . In the case of tiat present, an impedance value calculated during a time interval untilti-3, ti-2, ti-1, and ti may be applied to a parameter value. Meanwhile,impedance is reduced at ti. At this time, energy is not blocked.Predeterminedally, referring to FIG. 5 b showing an enlarged risingphase, in the case of tj, during time up to tj-3, tj-2, tj-1, and tj,impedance rise up to Zj-3, Zj-2, Zj-1, and Zj. At this time, a change(ΔZ) in the impedance continues to rise. This corresponds to a casewhere the parameter value exceeds the first threshold or becomes thefirst threshold or more. Accordingly, the RF energy may be blocked. Whenthe RF energy will be blocked at any point of time during the period inwhich the impedance rises may be different according to circumstances.Predeterminedally, a location is different depending on a set firstthreshold. If a high first threshold is set, the RF energy may beblocked at a higher temperature. If a low first threshold is set, the RFenergy may be blocked at a low temperature.

That is, the controller blocks RF energy if the following condition issatisfied.

Parameter>first threshold

Furthermore, impedance may be determined to have increased for apredetermined period if any one value of the mean (Zave) of impedancevalues during a period from the current to a predetermined time before,the product of an impedance value, a change (ΔZ) in the impedance value,and a change in the mean (ΔZave) of an impedance value is the firstthreshold or more. In this case, the parameter may be defined as any oneof the followings.

Parameter=Zave

Parameter=Z _(t) ×Z _(t-1) ×Z _(t-2) × . . . ×Z _(t-k)

Parameter=ΔZ

Parameter=ΔZave

In this case, t is the current time, and k is a set time interval. Inthis case, a determination of a parameter value after a predeterminedtime interval when RF energy is applied may be determined so thathandling can be performed in the ablation phase without handling achange in the initial impedance value.

A method of controlling the RF treatment apparatus when the ablationmode is applied is described below. FIG. 6 is a flowchart of the methodof controlling the RF treatment apparatus in the ablation preventionmode.

The method of controlling the RF treatment apparatus when the ablationmode is applied may include a step S100 of positioning an electrode in atissue, a step S200 of applying RF energy, a sensing step S300, a stepS400 of calculating impedance, a step S500 of determining whether aparameter exceeds a first threshold, and a step S600 of cutting off theRF energy.

The step S100 of positioning an electrode in a tissue corresponds to thestep of positioning the electrode close to a tissue that is a target oftreatment. When the skin is treated, the electrode may be brought incontact with the skin or the electrode including a plurality of microneedles may be inserted through the skin and positioned.

The step S200 of applying RF energy corresponds to the step of applyingRF energy in order to treat the tissue. In this case, the RF energy iscontrolled and applied depending on the state of the tissue throughfeedback control.

The sensing step S300 corresponds to the step of measuring a voltage,current and power applied to the electrode and a load including thetissue while the RF energy is applied. In this case, a unique impedancevalue may vary because the RF energy is applied to the tissue. Acorresponding voltage, current and power is measured in real time.

In the step S400 of calculating impedance, impedance is calculated usingthe result values measured in the sensing step S300. In this case, thecalculation is performed as an RMS.

The step S500 of determining whether a parameter exceeds a firstthreshold corresponds to the step of determining whether cut-off isnecessary in order to prevent excessive energy from being transferred tothe tissue. The application of the RF energy is cut off right beforeablation of the tissue in order to prevent the ablation from occurringbecause excessive RF energy is applied within a short time.

If a temperature is measured at this time, there is a difficulty inusing the temperature for feedback because time delay occurs.Accordingly, a point of time of cut-off is determined based on aparameter into which a change in the impedance (ΔZ) of the tissue hasbeen incorporated. In this case, the parameter may be determined asdescribed above with reference to the aforementioned function of thecontroller.

In other words, a parameter determined based on the “phase in which achange (ΔZ) in the impedance rises (impedance increment rising phase)”and “a value of the impedance during the risen phase (rising phase)”.When the parameter is the first threshold or more, the RF energy may beautomatically cut off. Furthermore, the parameter may be determined byincorporating the mean of impedance values during the rising phase inorder to reduce an error attributable to noise.

As a result, whether a step is a step right before ablation may bedetermined by sensing an electrical predetermined value of the tissueover time in the state right before the ablation, and thus ablation isprevented.

The step S600 of cutting off RF energy corresponds to the step ofcutting off the RF energy in order to prevent ablation if the parametervalue is determined to be higher than the first threshold.

FIG. 7 is an impedance and temperature graph of a tissue when theablation prevention mode is performed in the RF treatment apparatus. Asshown, when a parameter into which a sudden rise of impedance has beenincorporated reaches a first threshold when the impedance risessuddenly, RF energy is cut off so that a temperature of a tissue doesnot become a predetermined temperature or more. Accordingly, if a tissuehas different electrical characteristics depending on a person althoughthe tissue is located in the same portion, RF energy is cut off at adifferent point of time, thereby being capable of preventing ablationfrom occurring.

II. Coagulation Mode

Hereinafter, the coagulation mode that may be optionally applied by thecontroller is described in detail with reference to FIGS. 8 a to 12 b.

FIGS. 8 a and 8 b are conceptual diagrams when coagulation within atissue occurs. As shown, a treatment lesion within a tissue when theelectrode that is an invasive type and a bipolar type is used occursaround the electrode and on the path along which RF energy between theelectrodes is transferred. In this case, a temperature of the tissuerises as the RF energy is applied to the tissue, so the tissue becomes acoagulation state when the temperature is about 70 to 80° C. Thereafter,if the temperature further rises, the coagulation state changes into anablation state. It has been known that in treatment for purposes, suchas wrinkle improvement and a skin elasticity increase as in the skin,ablation is not preferred and it is helpful to treat a tissue in thecoagulation state.

FIG. 8 a shows a treatment volume (i) in which coagulation occurs whenRF energy is applied. If the RF energy is suddenly applied from thispoint of time, ablation rapidly occurs (ii) in the treatment volume ofthe tissue compared to an increase of the coagulation region (i), as inFIG. 8 b . In order to prevent such ablation and also increase thetreatment volume in which coagulation occurs, as shown in FIG. 8 c , amethod of repeatedly applying RF energy to a neighboring region throughinsertion/reinsertion or a method using a large electrode is used.However, such a method is not appropriate for rapid treatment and areduction of pain because a patient's pain increases due to therepetitive insertion and an insertion location needs to be preciselycontrolled.

FIG. 9 is a graph showing RF energy measurement values when RF energy isapplied within a tissue. As shown, when RF energy of a constant voltageis applied, RF power applied to a tissue has an initial peak value.Thereafter, the RF power tends to suddenly rise from a predeterminedpoint of time. Meanwhile, a temperature of the target tissue graduallyrises, and the temperature tends to gradually rise from a predeterminedpoint of time. At this time, when the temperature of the tissue rises,an impedance value of the tissue also rises. As a result, RF energy issuddenly applied to the tissue. In such a case, as described above withreference to FIGS. 8 a to 8 c , ablation in some regions rapidly occurscompared to an increase of the treatment volume in which coagulationoccurs. This occurs when the transfer of energy according to RF energyis faster than the transfer of heat toward surroundings within a targettissue.

The controller controls RF power so that a temperature of a tissuebecomes constant. In this case, the temperature of the tissue may beestimated based on a change in the impedance of the tissue. If theimpedance of the tissue is maintained within a constant range, thetemperature can also be maintained to a predetermined level.

The controller performs control of RF energy from a point of time aftera predetermined point of time, that is, from a point of time at whichcoagulation occurs after RF energy is applied. In this case, the sensorunit measures a voltage, current and power, and the controllercalculates an impedance value based on the voltage, current and power.Such calculation may be performed as an RMS.

The controller continues to monitor a change (ΔZ) in the impedance aftera predetermined point of time, that is, a first application time, forexample, after 50 ms (heat phase). Control may be performed when aninstant impedance change exceeds a predetermined range. That is, when achange in the accumulated impedance exceeds a predetermined numericalvalue for a predetermined time interval up to the current time, thecontroller applies RF energy by increasing or decreasing RF power sothat the impedance of a tissue can be maintained to a proper level. Inthis case, control of the RF power may be performed for a thirdapplication time.

A determination of whether the accumulated impedance exceeds thepredetermined numerical value may be made by comparing a parameter valueinto which a change in the impedance has been incorporated with a secondthreshold. In this case, the comparison of the parameter includescalculating impedance from the current to a predetermined time beforeevery sampling time cycle. For example, impedance values, such as theaverage of impedance, the average of impedance changes, the product ofimpedance, the product of the impedance mean, and the absolute value ofan impedance change, may be incorporated into the parameter.

Predeterminedally, if control is performed using the mean (Zave) ofimpedance values, the sensor unit senses RF energy, the mean of targetimpedance of a tissue from the current to a predetermined time beforemay be calculated, and whether the second threshold is exceeded may bedetermined. For example, if the current time is t and the predeterminedtime interval is 3T, the average of impedance may be defined as“Zave=(Z(t)+Z(t−T)+Z(t−2T)+Z(t−3T))/4.” Furthermore, if a treatmenttemperature is to be maintained, the controller may control RF energy sothat the mean is maintained within a predetermined range using the mean(Zave) of the impedance for the predetermined time interval. That is, ifthe mean (Zave) of the impedance is lower than the second threshold, thecontroller can maintain the average of the impedance within thepredetermined range by increasing RF power. In contrast, if the mean(Zave) of the impedance is higher than the second threshold, thecontroller can maintain the average of the impedance within thepredetermined range by decreasing RF power.

FIG. 10 is a flowchart of the coagulation mode, and FIG. 11 is adetailed flowchart of the energy control step of FIG. 10 .

As shown, a method of controlling the RF treatment apparatus when thecoagulation mode is performed according to the present invention mayinclude a step

S1100 of positioning an electrode, a step S1200 of applying RF energy, astep S1300 of determining whether a target tissue has reached atreatment temperature, and a step S1400 of controlling the RF energy.

The step S1100 of positioning an electrode corresponds to the step ofpreparing treatment by positioning the electrode in a target tissue, andmay be performed by bringing the electrode in contact with a surface ofthe target tissue, inserting the electrode into the target tissue orperforming a contact and insertion at the same time.

The step S1200 of applying RF energy corresponds to the step of applyingRF energy with predetermined power. In this case, the predeterminedpower may be a value previously set based on the size of the electrode,an array of the electrodes, the characteristics of the tissue, etc. Thepredetermined power may be determined based on an impedance valuethrough the step of initially calculating an impedance value of thetissue.

The step S1300 of determining whether the target tissue has reached atreatment temperature corresponds to the step of determining whether thetarget tissue has reached the treatment temperature by measuring the RFpower. RF power when it is applied to the tissue is monitored. If achange (ΔZ) in the impedance corresponds to a range within apredetermined range, it may be determined that the target tissue hasentered a stabilization step and has reached a coagulation temperature.

Furthermore, the step S1300 of determining whether the target tissue hasreached the treatment temperature may be started from a firstapplication time after the RF energy is applied. The reason for this isthat in the heat phase, an impedance value of the tissue is suddenlychanged and separate control of the RF power is not necessary.

The step S1400 of controlling the RF energy corresponds to the step ofcontrolling the RF power so that a volume corresponding to the treatmenttemperature is maximized for a predetermined time if the target tissuehas reached the treatment temperature.

Referring to FIG. 11 , the step S1400 of controlling the RF energy mayinclude a step S1410 of determining whether the first application timehas elapsed, a step S1420 of determining a change in the impedance ofthe tissue, a step S1430 of controlling the voltage of the RF generator,and a step S1440 of determining whether a third application has elapsed.

The step S1410 of determining whether the first application time haselapsed corresponds to the step of applying energy of preset RF powerwithout determining whether the target tissue has reached a treatmenttemperature during the time corresponding to the heat phase. In thisphase, impedance of the tissue may change suddenly, and thus the step isperformed because separate control is not necessary.

The step S1420 of determining a change in the impedance of the tissuecorresponds to the step of determining whether impedance of the tissuehas changed by deriving the impedance of the tissue. The impedance ofthe tissue may be derived by measuring a voltage, current and powervalue of the RF energy applied to the electrode. In this case, animpedance value of the tissue and a change in the impedance value may bederived every moment and used for control.

The step S1430, S1440 of controlling the voltage of the RF generatorcorresponds to the step of controlling the RF power by controlling thevoltage based on the impedance change derived in the step S1420 ofdetermining a change in the impedance of the tissue. That is, the RFpower is decreased (S1430) when the impedance value increases, and theRF power is increased (S1430) when the impedance value decreases. In thestep of controlling the voltage of the RF generator, the RF power iscontrolled so that the transfer rate of heat toward surrounding tissueshas the same level as the transfer rate of the RF energy transferredfrom the electrode in a local volume in which the treatment temperaturehas been reached. The target tissue that has reached the treatmenttemperature maintains the temperature, and the volume in which thetarget tissue has reached the treatment temperature is graduallyincreased. Furthermore, in control of the RF energy, the RF power may becontrolled using an accumulated value of the change (ΔZ) in theimpedance.

In the step S1450 of determining whether the third application haselapsed, whether the step S1430, S1440 of controlling the RF power hasbeen performed for a preset time is determined. If a preset thirdapplication time has elapsed, the RF energy is cut off and acorresponding cycle is terminated. A detailed numerical value of thethird application time is omitted because the third application time maybe different depending on the characteristics of a target tissue, theconfiguration of an electrode, etc.

FIGS. 12 a and 12 b are graphs showing RF energy measurement values whenthe coagulation mode is performed. FIG. 12 a shows a graph before thecoagulation mode is performed, and FIG. 12 b shows a graph after thecoagulation mode is performed.

As shown, although RF power is constant after a predetermined point oftime, the phase in which an impedance value of a tissue suddenly risesoccurs. In this case, ablation occurs as described above. In this case,if the RF power is controlled so that the impedance maintains a constantrange, the impedance can maintain a proper level as in FIG. 12(b). Inthis case, if control is performed based on a change (ΔZ) in theimpedance, an impedance change converges within a predetermined range.In such a case, if the impedance corresponds to the predetermined range,this means that a temperature of a target tissue is also maintainedwithin the predetermined range. Accordingly, a change (ΔZ) in theimpedance is monitored from a point of time at which coagulation occurs.The impedance may be maintained within a predetermined numerical valueby lowering the voltage of the RF power at a point of time at which thechange suddenly changes.

As a result, the volume in which coagulation occurs can be expandedbecause a tissue can be prevented from rising to a temperature or moreat which ablation occurs and the tissue can also be maintained to atreatment temperature.

Hereinafter, a detailed configuration of the RF treatment apparatusaccording to the present invention is described with reference to FIGS.13 and 14 .

FIG. 13 is a perspective view of the RF treatment apparatus according tothe present invention embodiment. FIG. 14 is an enlarged perspectiveview of a handpiece of FIG. 13 . The RF treatment apparatus according tothe present embodiment is an apparatus in which an insertion unit 10 isinserted into a skin tissue of the human body, for transferring energyinto the inside of the skin tissue. The insertion unit 10 of the presentembodiment includes a plurality of needles and may transfer energy tothe inside of a skin tissue through the end of the needles.

The treatment apparatus according to the present embodiment is describedin detail includes a main body 100, a handpiece 200 that a user cangrasp and perform treatment, and a connection unit 400 connecting themain body and the handpiece.

The RF generator and the controller (not shown) may be provided withinthe main body 100. As described above, the controller generates acontrol input to control the RF generator based on a sensing valuereceived from the sensor unit. In this case, the frequency of RF energymay be controlled depending on a patient's physical constitution,treatment purposes, a treatment portion, etc. For example, RF energyused for skin treatment may be controlled within a range of 0.1 to 10MHz.

An on/off switch 110 of power, a frequency control lever 120 capable ofcontrolling the frequency of RF energy generated by the RF generator,and a touch screen 130 on which a variety of types of informationincluding operating contents of the treatment apparatus are displayedand treatment information is displayed and in which a user can input acommand may be positioned on an external surface of the main body 100.

Meanwhile, the handpiece 200 is connected to the main body by theconnection unit 400. The connection unit 400 may transfer RF energy,generated by the RF generator of the main body, to a plurality ofneedles 320 corresponding to the insertion unit 10 of the aforementionedembodiment, and may transfer power from the main body, which isnecessary for various elements on the handpiece side to operate. Theconnection unit 400 is configured in a cable form and may use a cableincluding a plurality of metal lines covered with insulating coating.

A driving unit 210 and a cooling unit 40 are positioned within thehousing of the handpiece 200. The driving unit 210 is configured tolinearly move output terminals 211 provided at one end of the drivingunit in the length direction. As the output terminals 211 move linearly,the plurality of needles 320 disposed at the end of the output terminalsmay appear and disappear to an external surface of a contact surface ofthe handpiece. Accordingly, when the driving unit 210 is driven, theplurality of needles 320 may be inserted into a patient's tissue or maybe drawn out from the tissue. The driving unit 210 may be formed of alinear actuator using a solenoid or a hydraulic/pneumatic cylinder.

A handpiece manipulation unit 230 and a handpiece display unit 220 maybe provided on an external surface of the handpiece 200. The handpiecemanipulation unit 230 is configured to manipulate the on/off of thehandpiece, control the insertion depth of the insertion unit 10 orcontrol the amount of energy applied through the insertion unit 10. Thehandpiece display unit 220 may display a variety of types of informationfor a user during a setting mode or treatment. Accordingly, the user caneasily control treatment contents during treatment through the handpiecemanipulation unit 230 in the state in which the user has grasped thehandpiece, and can easily check treatment contents through the handpiecedisplay unit 220.

A tip module 300 is provided at the end of the handpiece. The tip moduleincludes the plurality of needles 320 and may be detachably positionedin the main body 201 of the handpiece. Predeterminedally, a base 301forms the bottom of the tip module. Outward protruded detachmentprotrusions 307 are formed in the outside wall of the base. A hollowthrough which a cooling wind from the cooling unit 40 can pass may beformed in a portion that belongs to the base 301 and that neighbors theprotruded parts of the needles. Furthermore, a plurality of throughholes may be formed in an outside portion that does not neighbor theprotruded parts of the needles other than the protruded parts of theneedles so that a cooling wind can be discharged. Guide grooves 241guiding the detachment protrusions and anti-separation grooves 242 forpreventing the detachment of the detachment protrusions 307 guided alongthe guide grooves 241 are formed in a recess part 240 to which the tipmodule is coupled on the handpiece side. Furthermore, the detachmentprotrusions 307 of the tip module are installed on the handpiece in sucha manner that they are guided along the guide grooves 241 and coupled tothe anti-separation grooves 242. Meanwhile, the tip module may beconfigured to cool the needles 320 by the driving of the cooling unit40, but to seal the inside and outside of the handpiece in order toprevent an externally drained cooling wind from affecting a surface ofthe skin. In this case, the sealing means that a gap is formed betweenthe handpiece and the tip module to the extent that a surface of theskin is not influenced by an externally drained cooling wind.

In this case, what the tip module is detachably positioned in thehandpiece as in the present embodiment is an example. The tip module maybe integrated with the handpiece.

Predeterminedally, the electrode 11 may be formed of a micro electrode11 having a diameter of about 5 to 500 μM. The electrode 11 is made of aconductive material so that it can deliver RF energy. A portion thatbelongs to a surface of each electrode 11 and that excludes the frontpart is made of an insulating material 321 so that RF energy is nottransferred to a tissue. Accordingly, part of the front part of eachneedle functions as the electrode 11. RF energy is applied to the tissuethrough the front part. Accordingly, RF energy can be selectivelytransferred to a portion where the end of the electrode 11 is positionedduring treatment.

The front S of the tip module may form a portion that neighbors or comesinto contact with the skin of a patient during treatment. The pluralityof through holes 302 through the plurality of electrodes 11 appears anddisappears is formed in the front.

At least one hole 303 through which the output terminals 211 can pass isprovided at the bottom of the tip module. When the driving unit 210operates, the output terminals 211 pressurize a board 13 while linearlymoving along the hole 303. The back of the board 13 is seated in asupport 304 within the tip module, and the front thereof is pressurizedby an elastic member 330 positioned within the tip module. When theoutput terminals 211 moves and pressurizes the board 13, the board 13advances while being separated from the support 304, and the pluralityof electrodes 11 is inserted into a skin tissue while being protrudedtoward the front of the through hole 302. Furthermore, when the outputterminals 211 retreat by the driving of the driving unit 210, the board13 retreats by restoring force of the elastic member 330 and theplurality of electrodes 11 also returns to the inside of the tip module.Although not separately shown, a separate guide member for guiding thepath along which the board moves may be further provided.

Although not shown in the drawing predeterminedally, the circuit of theboard 13 may be configured to be electrically connected to the RFgenerator of the main body when the tip module is positioned in thehandpiece. Alternatively, the circuit of the board may be configured tobe selectively electrically connected to the RF generator when the boardis pressurized by the output terminals 211 (e.g., the electrode 11 isformed at the end of the output terminal and electrically connected tothe board when the electrodes is pressurized).

In addition, the present invention may provide a treatment method usingRF energy. In the skin treatment method using RF energy, the electrodeis positioned in a tissue, the tissue is heated by applying RF energy,the RF energy applied to the tissue is measured, impedance of the tissueto which the RF energy is applied is calculated, a parameter into whichthe impedance has been incorporated is compared with a threshold,whether to cut off the RF energy is determined based on the threshold,and the skin is treated.

A voltage, a potential and power are measured from the RF energy appliedto the tissue. The RMS of impedance of the tissue may be calculatedbased on the voltage, potential and power. While the RF energy isapplied, the RF energy is periodically measured according to a samplingtime, impedance is calculated, and control is performed using impedancecalculated from the current to a predetermined time before.

In this case, a curer may perform treatment selectively using one of theablation prevention mode and the coagulation mode as follows. In thiscase, in the two modes, RF energy may be applied based on the parameterdescribed in the method of controlling the RF treatment apparatus.

In the ablation prevention mode, if impedance suddenly rises and aparameter value is a first threshold or more, RF energy is cut offbefore ablation of a tissue occurs based on a symptom that the ablationmay occur, thereby preventing a temperature of the tissue from rising.Thereafter, a skin treatment method using RF energy by changing theposition of an electrode may be repeatedly performed.

In the coagulation mode, RF energy is controlled so that the periodduring which a tissue is maintained to a treatment temperature can beextended. A temperature of the tissue is estimated and RF energy iscontrolled based on a parameter into which an impedance value has beenincorporated. Accordingly, the tissue does not rise up to a temperatureat which ablation occurs and is maintained to a temperature at whichcoagulation occurs, so the region in which coagulation occurs isincreased.

The aforementioned RF treatment apparatus, method of controlling the RFtreatment apparatus, and skin treatment method using RF energy accordingto the present invention can be used to control power of RF energy byderiving an impedance value of a tissue without measuring thetemperature and impedance of the tissue when the RF energy is applied.Accordingly, rapid and accurate control can be performed. Furthermore,there are effects in that unnecessary damage to a tissue can beprevented, stability can be improved, and the recovering of a patientcan be increased by cutting off RF energy before ablation of the tissueoccurs based on a parameter. Furthermore, there is an effect in that atreatment effect can be maximized because a treatment volume is expandedby maintaining a tissue to a coagulation temperature for a long time.

1. An RF treatment apparatus, comprising: an RF generator generating RFenergy; an electrode applying the RF energy for a target tissue; asensor unit configured to sense the RF energy; and a controller that isconfigured to: control output of the RF generator, receive a sensingvalue from the sensor unit during applying the RF energy to a targettissue in real time, calculate impedance of the target tissue in realtime, cut off the RF energy before the tissue enters an ablation phasebased on a rate of change of impedance in real time.
 2. The RF treatmentapparatus of claim 1, wherein: the controller cuts off the RF energywhen a parameter exceeds a threshold, and wherein the parameter is basedon the rate of change of impedance.
 3. The RF treatment apparatus ofclaim 2, wherein the parameter is defined as a product of a rising timein which impedance increases for the three consecutive time periods andthe rate of change of impedance for the rising time.
 4. The RF treatmentapparatus of claim 2, wherein the parameter is defined as a product of aspecific time and an average of rate of change of impedance up to thespecific time.
 5. The RF treatment apparatus of claim 2, wherein: thesensor unit measures current, a voltage and power applied to theelectrode, and the controller calculates the rate of change of impedanceas a root mean square (RMS) when calculating the impedance.
 6. The RFtreatment apparatus of claim 5, wherein the controller controls anoutput voltage of the RF generator so that the power does not exceed aspecific range.
 7. The RF treatment apparatus of claim 2, wherein theelectrode comprises at least one of a contact type and an insertiontype.
 8. A method of controlling an RF treatment apparatus, comprisingsteps of: applying RF energy to a tissue through an electrode;calculating impedance of the tissue during applying the RF energy to atissue in real time; calculating a parameter based on a rate of changeof impedance using impedance values or changes during which RF energy isapplied in real time; determining that the tissue is on the verge of anablation phase by comparing the parameter to a threshold; and cuttingoff the RF energy when the parameter exceeds the threshold.
 9. Themethod of claim 8, wherein the parameter is defined as a product of arising time from a current time to a specific time and the rate ofchange of impedance for the rising time.
 10. The method of claim 8,wherein the parameter is defined as a product of a rising time from acurrent time to a predetermined time before and an average of rate ofchange of impedance for the rising time.
 11. The method of claim 8,wherein the step of determining that the tissue is on the verge of anablation phase is performed after a specific time from a point of timeat which the RF energy is applied.
 12. The method of claim 8, whereinthe step of positioning the electrode in the tissue is performed by atleast one of a contact and insertion of the electrode on and into thetissue.
 13. A skin treatment method using RF energy, comprising stepsof: positioning an electrode in a tissue; heating the tissue to atreatment temperature by applying RF energy to the electrode; measuringthe RF energy applied to the tissue during applying RF energy in realtime; calculating a rate of change of impedance of the tissue based onthe measured RF energy; comparing a parameter based on the rate ofchange in the impedance of the tissue to a threshold; cutting off the RFenergy when the tissue is the tissue is on the verge of an ablationphase based on a result of the comparison between the parameter and thethreshold in order to prevent ablation of the tissue.